Alloy steel



Patented Apr. 23, 1935 ALLOY STEEL Joseph V. Emmons, Shaker Heights,Ohio, as-

signor to The Cleveland Twist Drill Company, Cleveland, Ohio, acorporation of Ohio No Drawing. Original application December 22,

1934, Serial No. 758,754.

Divided and this application March 11, 1935, Serial No. 10,390

13 Claims.

This application is a division of my co-pending application Serial No.758,754, filed December 22,

This invention relates to ferrous alloys' and l more particularly toalloy steels in which tungsten is employed as a principal alloyingconstituent.

More specifically, this invention relates to that type of ferrous alloysor alloy steels which is employed in .the form of cutting tools andwearl resisting parts and which type is commonly referred to by thosefamiliar with the art as an alloy tool steel. I I

As is well known to those familiar with the art, alloy tool steels have,in the past, been made with tungsten as the principal alloyingconstituent and the types commonly known as high speed steels are atpresentthe standard commercial tool steels for high duty machining ofmetallic substances. The tungsten high speed steel most widely usedcommercially at the present time is essentially an alloy of carbon andiron with approximately 18% tungsten, 4% chromium and 1% vanadium. Thisstandard type is commonly known as 18-4-1 high speed steel. In addition,such steel contains minor quantities of such alloying elements andimpurities as manganese, silicon, copper, sulphur, phosphorus, arsenic,tin, etc. Such elements as cobalt, nickel, uranium'and tantalum aresometimes added to sgcure certain changes in the properties of the seel.

In my previous U. S. Patent No. 1,937,334 is disclosed the fact that avery satisfactory steel capable of being satisfactorily used for thesame purposes for which 18-4-l high speed steel has been used may besecured, if to a steel in which molybdenum is the principal alloyingingredient, minor amounts of tungsten are added and if the amount ofsuch tungsten is present in a defined a proportional relationship to theamount of molybdenum present. It has been explained that theunexpectedly desirable results secured by the addition of minor amountsof tungsten to a molybdenum steel as taught in my above identifiedpatent is due to a powerful auxiliary effect which such minor amount oftungsten has upon the molybdenum content of the alloy. The desirableresults secured by the addition of such minor amounts of tungsten to amolybdenum steel are greater than any results which'would be expectedupon the theory oiequivalency of tungsten and molybdenum as taught inthe prior art.

The present invention relates to the discovery i that molybdenum, whenadded to a ferrous alloy composition, in which tungsten is the principalalloying element, and when thus added in amounts which bear a certainproportional relationship to the amount of tungsten present, has

a powerful auxiliary effect upon such steel. Such results areconsiderably more pronounced than 5 those usually achieved by theaddition of molybdenum to high tungsten steels in accordance with thepractices in the prior art.

It is a principal object of this invention, therefore, to provide aferrous alloy composition, or more particularly, a ,tool steel of thetype in which tungsten is a principal alloying constituent and to whichthere has also been added a minor amount of molybdenum for its powerfulauxiliary eiiect, thus producing a steel which, when used for purposesof cutting tools, wear-resisting parts and the like, has performancecharacteristics equal to and in certain respects superior to those ofcomparable steels in the prior art.

It is a further object of my invention to provide a. high speed toolsteel of the high tungsten type having cutting or wear-resistingproperties superior to the cutting or wear -resisting properties of thestandard 18-4-1 tungsten high speed tool steel.

It is also an object of my invention to provide a high speed tool steelof the high tungsten type substantially equal. in cutting orwear-resisting qualities to the standard 18-4-1 high speed tool steelbutwhich contains a materially lesser amount of the expensive ingredienttungsten.

Itisalso-an object of my invention to provide a high speed tool steel ofthe type in which tungsten is the alloying element having the dominating effect and which steel has a lower. specific gravity than comparablesteels of this type known to the prior art.

It is a further object of my invention to provide high speed tool steelswhich may attain a higher degree of secondary hardness after hardeningand 40 tempering than is usual with the standard l8-4-l type of steel.

It is still another object of my invention to provide steels having highsecondary hardness and also having high values of strength and ofplasticity developed simultaneously by theme heat 7 treatment so thatsaid steels exhibit exceptional toughness.

Other objects of my invention will appear as the description proceeds.

some approved combinations of ingredients embodying my invention, suchdisclosed means constituting, however, but a few of the various forms inwhich the principle of the invention may be used.

The present invention relates, as previously indicated, to the discoverythat certain minor amounts of molybdenum, as hereinafter more fullydefined, when added to a ferrous alloy composition of the type in whichtungsten is a principal alloying ingredient, have a powerful aux iliaryalloying efiect thereon, considerably greater than any effect ofmolybdenum previously observed in such alloy compositions.

More specifically, thisinvention comprises the discovery that in theclass of alloy tool steels in which tungsten is the dominating alloyingelement, there is a definite relationship between tungsten andmolybdenum which, is properly observed, produces unexpectedly favorableresults.

This relationship is made effective by adding to such steels auxiliarymolybdenum in amounts from about 12% to about 28% of the amount oftungsten present. Such additions have been found to greatly andunexpectedly increase the cutting and wearing quality of tools made fromthe-steel.

'The above given range of from about 12% to 28% for the ratio betweenthe tungsten and molybdenum may be conveniently divided into thefollowing narrower ranges, viz.:--

Molybdenum from about 12% to about 15% of the tungsten present;

Molybdenum from above 15% to about 25% of the tungsten present;

Molybdenum from above 25% to about 28% of the tungsten present.

The previously defined range for the ratio between the two elements maybe further divided in the following manner,

Molybdenum from about 12% to about 20% of the amount of tungstenpresent; and

Molybdenum from above20% to about 28% of the amount of tungsten present.

In the ensuing description wherein will be found a disclosure of a largenumber of alloys, in whichthe above defined proportional relationshipbetween tungsten and molybdenum is maintained, it will be noted thatthere are certain groups of compositions which may be convenientlyclassified in the above defined manner.

The broad limits of composition wlthinwhlch this invention resides areas follows:-

to about 1.60% to about 3.00%

Carbon about 0.15% Silicon I atrace Chromium about 3.25% to about 6.00%Tungsten about 8.00% to about 20.00%, Vanadium None to about 6.00%Molybdenum about 0.96% to about 5.60% Cobalt None to about 16.00%

the remainder being substantially iron together i with such otheralloying elements and impurities as are sometimes found in this type ofalloy composition.

A somewhat narrower range of compositions is as follows:

Carbon about 0.65% to about 0.90% Silicon about 0.20% to about 2.20%Chromium about 3.37% to about 4.98% Tungsten about 10.32% to about19.00%

Vanadium about 0.45% to about 3.09%

Molybdenum about "1.24% to about 5.32% Cobalt None to about 14.00%

1 the remainder being substantially iron together with such otheralloying elements and impurities as are sometimes found in this type ofalloy composition.

A still narrower range of compositions is as follows:-

Carbon about 0.65% to about 0.85% Silicon about 0.27% to about 1.00%Chromium about 3.42% to about 4.73% Tungsten about 11.04% to about16.50% Vanadium about 0.68% to' about 2.46% Molybdenum about 1.32% toabout 4.62%

Cobalt None to about 12.00%

Example No. C Cr W M0 81 Va Co Ratio Afitllfll Percent Percent PercentPercent Percent Percent Percent Percegt 4.00 00 Attention is directed athe fact that in the foregoing table the various compositions arepreciably, thus reducing the weight of steel required to make a tool orother article of manufacture.

From the foregoing description, it will be apparent that my inventionrelates not to the substitution of molybdenumfor tungsten in high speedtool steels as has been suggested in certain instances in the prior art,but instead to the production of a new type of tungsten steel in which aspecific minor amount of molybdenum Tampering range for maximumsecondary hardness "F.

Maximum torsional Plasticity strength at maximum bserved g fish? hcondition Rockwell B condition scale 2350 About 1040 040-1090 s asasseasassse as wwwwwwwwwwwwwwwmmwws seeseaasssssessssass 1 For adescription of the method of determining theseproperties refer toProceedings American Society for Testing Materials" vol. 31

part II (1931), page 47. v

Certain maximum values, such as hardness, given in the foregoing table,are those which have been observed; however, it is possible that highervalues may be attainable by different heat treatments.

While the above values, indicating the best hardening and temperingranges, are the results of actual observations, itis recognized thatthey are a matter of opinion only and for specific purposes, desirableheat treatments might be found outside these values.

It will be observed that the specific gravities of the examples listedin the above table are materially lower than those of the 18-4-1 type ofhigh speed steel, the specific gravity of which is generally in excessof 8.60.

Particular attention is called to Examples No. 8 and 14. These steelsshowed outstanding cutting quality when used as drills, their drillingperformance definitely exceeding that of the drills made of 18-4-1 highspeed steel with whichthey were compared.

Particular attention is also called to the high secondary hardnessdeveloped by Examples Nos. 3, 6, 9, 10, 11, 12, 14, 16, 23. Hardnessesin excess of Rockwell C 66 are regarded as being above those ordinarilydeveloped in the 18-4-1; type of high speed steel.

Attention is also called tothe high tempering range which is recordedfor Example 16. The

values of 940 to 1190 indicate a broad range and ously.

is used for its powerful auxiliary eifect in increasing the cutting andwearing qualities of such steel. By the addition of the auxiliaryquantities of molybdenum in the above defined specific ratio to .theamount of tungsten present, I have beenable to produce a high speedsteel of the tungsten type having cutting properties better than thoseof the molybdenum-free tungsten steels of the prior art and also betterthan certain other molybdenum-containing tungsten steels of the priorart which lie outside the above specified range of ratios of molybdenumto tungsten and with which comparisons have been made.

A wide variety of heat treatments may be employed in connection with theabove mentioned steels, includingamong others hardening tempering,carburizing, and nitriding, for the purpose of developing specificuseful properties in articles made from such steels. It should be notedthat the tempering and nitriding operations may, if desired, be carriedout simultane- If desired, steels of the above compositions may bedeposited as weld metal for the purpose of producing localized cuttingor wear-resisting portions of an article of manufacture.

Steels of some of the above compositions, due to their great strengthand toughness, are suitable for use as supporting and auxiliary wearingparts in composite tools, employing primary cutting edges or wearingsurfaces formed on elements of hard non-ferrous metallic compositions.

Exceptional hardness is obtainable by appropriate heat treatment ofcertain of the abovementioned compositions. This makes possible toolsparticularly suitable for machining materials of greater hardness thanthose at present considered mechinable by steels of the 18-4-1 highspeed steel type. v

Steels made in accordance with this invention may beproduced withextreme hardness and'a low degree of toughness. Such steels may beutilized in composite tools by supporting them with stronger or toughersteels of the same or other compositions.

Certain compositions made in accordance with this invention have a grainstructure, as cast, so fine as to make practicalthe production of sometypes of tools, cast to substantially their finished shape, which do notrequire hot work for grain refinement to fit them for use.

The resistance of certain compositions made in accordance with thisinvention to grain growth at temperatures approaching the melting point,makes possible the production therefrom of certain articles ofmanufacture by various processes requiring a high degree of-plasticflow, such as die forging, pressing and extruding.

As is well known to those familiar with the art, any specification for aparticular alloying composition must permit of certain variations due tothe fact that in making up the steel it is extremely difficult, if notimpossible, to commercially produce a composition exactly like a givenspecification. It is to be understood, therefore, that throughout thedescription and claims where I have used figures to denote definiteamounts and ranges, such amounts and ranges are to be construed toinclude the range of variations usually'permissible inmaking up steel togiven specifications.

It is understood that in the compositions specifled therein, minoramounts of other alloying elements and impurities such as manganese,nickel, titanium, tantalum, uranium, copper, aluminum, sulphur,phosphorus, arsenic, tin, etc., may be included and when the phrase thebalance being substantially all iron is used, it is intended to includeminor amounts of such elements.

Other forms may be employed embodying the features of my inventioninstead of the one here explained, change being made in the composition,provided the elements stated by any of the following claims or theequivalent of such in the amounts stated elements be employed.

I therefore particularly point out and distinctly claim as my invention:7

-1. A ferrous alloy comprising: carbon from about 0.15% to about 1.60%;chromium from .about 3.25% to about 6.00%; tungsten from about 8.00% toabout 20.00%; molybdenum from twelve and one-half per cent totwenty-eight per cent of the amount of tungsten present; silicon from asubstantial amount to about 3.00%; cobaltabout 3.25% to about 6.00%;tungsten from about 11.04% to about 16.50%; molybdenum from twelve andone-half per cent to twenty-eight per cent of the amount of tungstenpresent; silicon from a substantial amount to about 3.00%; cobalt from asubstantial amount to about 16.00%: and the remainder beingsubstantially all iron.

4. A ferrous alloy comprising; carbon from about 0.15% to about 1.60%;chromium from about 3.25% to about 6.00%; tungsten from about 8.00% toabout 20.00%; molybdenum from twelve and one-half percent to fifteen percent of the amount of tungsten present; silicon from a substantialamount to about. 3.00% cobalt from a substantial amount to about 16.00%;and the remainder being substantially all iron.

5. A ferrous allow comprising: carbon from about 0.65% to about 0.90%;chromium from about 3.37% to about 4.98% tungsten from about 10.32% toabout 19.00%; twelve and one-half per cent to fifteen per cent of theamount of tungsten present; silicon from about 0.20% to about 2.20%;cobalt from a substantial amount to about 14.00% and the remainder beingsubstantially all iron.

6. A ferrous alloy comprising: carbon from about 0.65% 'to about 0.85%;chromium from about 3.42% to about 4.73%; tungsten from about 11.04 toabout 16.50% molybdenum from twelve and one-half per centto fifteen percent of the.

amount of tungsten present; silicon from about 0.27% to about 1.00%;cobalt from a substantial amount to about 12.00%; and the remainderbemolybdenum from 8.00% to about 20.00%; molybdenum from fifto about14.00%; and the remainder being substantially all iron.

9. A ferrous alloy comprising: carbon from about 0.65% to about 0.85%;chromium from about 3.42% to about 4.73%; tungsten from about 11.04% toabout 16.50%; molybdenum from fifteen per cent to twenty per cent of theamount of tungsten present; silicon from about 0.27%v

to about 1.00%; cobalt from a substantial amount to about 12.00%; andthe remainder substantially all iron.

10. A ferrous alloy comprising: carbon from about 0.15% to about 1.60%;chromium from about 3.25% to about 6.00% tungsten from about 8.00% toabout 20.00%; molybdenum from twenty per cent to twenty-eight per centof the amount of tungsten present; silicon from a substantial amount toabout 3.00%; cobalt from a substantial amount to about 16.00%; and theremainder being substantially all iron.

11. A ferrous alloy comprising: carbon from about 0.65% to about 0.90%;chromium from about 3.37 to about 4.98%; tungsten from about 10.32% toabout 19.00 molybdenum from twenty per cent to twenty-eight per cent ofthe amount of tunsten present;' silicon from about 0.20% to about 2.20%;cobalt from a substantial amount to about 14.00% and the remainder beingsubstantially all iron.

12. A ferrous alloy comprising: carbon from about 0.65% to about 0.85%;chromium from about 3.42% to about 4.73%; tungsten from about 11.04% toabout 16.50% molybdenum from twenty per cent to twenty-eight per cent ofthe amount of tungsten present; silicon from about 0.27% to about 1.00%;cobalt from a substantial amount to about 12.00%; and the remainderbeing substantially all iron.

13.A tool formed of a ferrous alloy comprising: carbon from about 0.15%to about 1.60%; chromium from about 3.25% to about 6.00%; tungsten fromabout 8.00% to about 20.00%;

molybdenum from twelve and one-half per cent to twenty-eight per cent ofthe amount of tungsten present; silicon from a substantial amount toabout 3.00%; cobalt from a substantial amount to about 16.00%; and theremainder being substantially all iron.

JOSEPH V. EMMONS.

